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Make 16MHz from 32MHz Cheap

Make 16MHz from 32MHz Cheap

Make 16MHz from 32MHz Cheap

(OP)
I was wondering if anyone knew of a cheap way to make 16MHz from a 32MHz clock very cheaply.  I also need this to be stable.  The 32MHz drives one processor, and the 16MHz will drive another.

Thanks

RE: Make 16MHz from 32MHz Cheap

Why not use a flip flop set up to toggle?  This will divide the incoming frequency by two.

best of luck,
Stan

RE: Make 16MHz from 32MHz Cheap

Go with a PLL.  If these are clock signals, then don't mess around.  By the way, do these clock have to be in sync?

RE: Make 16MHz from 32MHz Cheap

TIs 74AHCT is good for 60MHZ, $.11 to $.38 ea. for 1000
( depending package etc.)

<nbucska@pcperipherals.com>

RE: Make 16MHz from 32MHz Cheap

(OP)
The two processors communicate asyncronously.  Would there be extra EM emissions due to using a flip-flop?  The second processor is a SCSI controller.  I need to ensure data integrity.  I am not quite sure how the flip-flop would effect that.

RE: Make 16MHz from 32MHz Cheap

Did you think that there are no flip-flops in either processor?

EM control is done through proper grounding, shielding and bypassing.  A poor design will cause inverters to have problems.

TTFN

RE: Make 16MHz from 32MHz Cheap

Well....... In general, I would agree, except in this case, perhaps simply inserting flop could cause some unforseen effects.  If the original signal has rise and fall times in the 50-100ns range, and the flop is in the 5-10ns range, there might be some EM issues.  BUT, the way to fix those issues is by doing exactly what you stated.

RE: Make 16MHz from 32MHz Cheap

True enough, but he is talking about a 32 Mhz clock, which means a half-period of 15.6 ns, so rise and fall times have to on the order of 5 ns or better to begin with.

TTFN

RE: Make 16MHz from 32MHz Cheap

(OP)
Flip flop it is.  Thank you all for your help.

RE: Make 16MHz from 32MHz Cheap

If the rise/fall is slow add delay into the /Q to D
feedback. ( IC or RC )

<nbucska@pcperipherals.com>

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